1. Field of the Invention
The present invention relates to novel compositions of matter comprising aqueous formulations of a cationic organic compound and a xanthan gum, and, more especially, to aqueous plant protection compositions comprising a cationic active agent.
2. Description of the Prior Art
Xanthan gum, because of its thickening properties, its high suspending ability and its particular rheology, is widely used in various industries, particularly in the food, construction, textile, paint, paper, and cosmetic industries, and also in the agriculture and petroleum industries, etc.
Xanthan gum is an anionic heteropolysaccharide which consists of D-glucose, D-mannose and D-glucuronic acid units, with acetyl and pyruvate radicals bonded to the mannose units. Its molecular weight is greater than 10.sup.6. As it is advantageous in the aforesaid different applications to have a relatively low concentration of the thickening agent, the industrial grades currently available commercially have high viscosities, corresponding to molecular weights ranging from 3.times.10.sup.6 to 5.times.10.sup.6.
In view of its anionic character, xanthan gum is considered to be generally incompatible with cations, thus militating against its formulation therewith. Moreover, it is known in the agricultural chemicals field to use xanthan gum as an agent to thicken aqueous compositions containing a water soluble active pesticidal agent, or as a stabilizing and suspension agent for flowable aqueous dispersions containing a finely divided active agent ("flowables"). These solutions or dispersions are supplied commercially in the form of a concentrate with 20% to 60% active material and approximately 0.02 to 2% xanthan gum. However, if the active agent is water soluble, this application is limited, in actual practice, to nonionic or anionic materials.
A user, who in certain cases wishes (in order to avoid several manipulations) to mix the dilute dispersion of a water insoluble pesticide in water with a water soluble pesticide, such as a quaternary ammonium salt, is thus confronted with a particular problem. It has been found that with low xanthan concentrations in dilute formulations, a complex is formed with the quaternary ammonium compound, which results in the formation of dense fibers that are insoluble in water. In addition to the fact that the formation of the complex reduces the pesticidal activity, considerable difficulties are encountered during spraying in the field because of the clogging of the spray nozzles by the insoluble fibers.